JP2009244618A - Optical input/output terminal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical input/output terminal reducing stress and thermal damage to an optical fiber. <P>SOLUTION: The optical input/output terminal including an optical fiber and an optical fiber covering part covering the optical fiber, includes an optical fiber body having an optical fiber exposing part exposing the optical fiber in at least one part of the optical fiber covering part, a cylindrical body having an inner hole housing at least the optical fiber exposing part, a sealant arranged between an inner circumference face of the cylindrical body and the optical fiber part and blocking one part of the inner hole, and a base having at least one through-hole holding the cylindrical body and inserted with at least one part of the cylindrical body in the through-hole. The optical exposing part is separated away from the inner circumference face of the cylindrical body via a gap in an insertion part inserted into the through-hole of the cylindrical body, and the sealant is arranged between an inner circumference face of a non-insertion part of the cylindrical body excluding the insertion art and the optical fiber exposing part. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an optical input / output terminal used in an optical fiber mounting portion of equipment and components used in an optical communication system or the like.

  Some devices and parts used in an optical communication system are required to have long-term reliability depending on the environment and period of use. For example, devices and parts such as submarine optical cable repeaters are required to have a relatively high long-term reliability because the replacement work is complicated. The jacket of the device or component is made of metal and has a structure that can be hermetically sealed to prevent intrusion of moisture and the like from the outside. Therefore, in such a device / part, the structure of the optical fiber mounting portion is an important issue.

  In particular, in an optical communication module such as a semiconductor laser module or a semiconductor amplifier module used for optical communication, an optical element such as a semiconductor laser housed in the housing is prevented from being deteriorated due to condensation. In order to extract light from the optical element to the outside, it is necessary to introduce an optical fiber into the casing without impairing the airtightness of the casing.

  As a method of realizing such an airtight structure, an optical fiber having a metal film on its outer surface is inserted into a metal cylinder (optical fiber fixing portion), and the optical fiber and metal cylinder having a metal film applied thereto. The airtightness between the optical fiber and the metal cylinder is ensured by fixing the body with solder. Further, the metal cylinder is inserted into an opening provided on the wall surface of the casing, and is fixed to the casing by soldering or welding in order to ensure airtightness with the outside. With such a structure, the optical fiber is introduced into the housing of the optical communication module while ensuring airtightness to the outside.

As a conventional example using this method, as shown in FIG. 5, an optical fiber having a metal film applied to the outer surface of an optical fiber is inserted into a pipe member (metal cylinder) and Then, solder is poured into the optical fiber to provide an airtight seal, and the pipe member and the optical fiber covering portion are fixed with an adhesive, and then the pipe member is welded to the opening of the wall surface of the housing. An optical input / output terminal is proposed (see Patent Document 1).
JP-A-8-15572

  However, in the optical input / output terminal described in Patent Document 1, since the solder sealing portion is surrounded by a separate substrate, stress concentrates on the solder sealing portion due to the difference in thermal expansion coefficient, and solder sealing is performed. There is a possibility of affecting the airtight characteristics of the part. Further, in this optical input / output terminal, there is a possibility that microcracks are generated in the glass portion of the optical fiber due to the stress concentration, and the optical fiber is damaged.

  The present invention has been made paying attention to such problems, and the object of the present invention is to provide an optical input / output terminal with reduced long-term reliability in which stress acting on the optical fiber is reduced.

  In view of the above problems, an optical input / output terminal according to the present invention includes an optical fiber and an optical fiber coating portion that covers the optical fiber, and at least a part of the optical fiber coating portion includes the optical fiber. An optical fiber body having an exposed optical fiber, a cylindrical body having an inner hole in which at least the optical fiber exposed section is accommodated, and an inner peripheral surface of the cylindrical body and the optical fiber exposed section. At least one sealing agent that closes a part of the inner hole and a through hole that holds the cylindrical body, and at least a part of the cylindrical body is inserted into the through hole, and A base for fixing the cylindrical body, and the optical fiber exposed portion is spaced apart from the inner peripheral surface of the cylindrical body via a gap in the insertion portion inserted into the through hole of the cylindrical body. And the sealing agent is the cylinder excluding the insertion portion. Characterized in that it is arranged between the non-insertion portion inner peripheral surface of the body and the optical fiber exposed portion.

  Moreover, in this invention, it is preferable that the said cylindrical body has a groove part in the internal peripheral surface of the site | part by which the said sealing agent is arrange | positioned, and a part of said sealing agent has penetrated into this groove part.

  Furthermore, in this invention, it is preferable that the said groove part is formed over the perimeter of the internal peripheral surface of the site | part by which the said sealing agent is arrange | positioned.

  Furthermore, in the present invention, it is preferable that the cylindrical body has a step portion larger than the diameter of the through hole on the outer peripheral surface, and is fixed in contact with the surface portion of the base body at the step portion.

  Furthermore, in this invention, it is preferable to fix the said level | step-difference part and the surface part of the said base | substrate with an adhesive agent.

  Furthermore, in the present invention, it is preferable that the sealant is made of low-melting glass. When the sealant is made of low melting point glass, pretreatment such as metallization treatment on the exposed portion of the optical fiber becomes unnecessary.

  Furthermore, in the present invention, the adhesive preferably has a lower melting point than the sealing agent.

  Thus, according to the present invention, the optical fiber is separated from the inner peripheral surface of the cylindrical body via the gap, and the inner peripheral surface and the optical fiber in the non-insertion portion of the cylindrical body into the base body Is sealed with a sealant, reducing stress concentration on the sealing portion due to the difference in thermal expansion coefficient between the base and the sealing portion, and stabilizing the hermetic properties of the sealing portion. it can. Furthermore, since the stress concentration in the sealing portion is reduced, the occurrence of microcracks in the optical fiber caused by the stress concentration can be reduced.

  Further, in the present invention, if the cylindrical body has a groove on the inner peripheral surface of the portion where the sealing agent is disposed, and a part of the sealing agent enters the groove, sealing is performed. Since the position of the agent can be controlled, sealing can be performed under stable conditions.

  Moreover, in this invention, if the said groove part is formed over the perimeter of the internal peripheral surface of the site | part by which the said sealing agent is arrange | positioned, it will control efficiently that a sealing agent flows out to another site | part. Can be fixed at a more stable position.

  Further, in the present invention, if the cylindrical body has a step portion larger than the diameter of the through hole on the outer peripheral surface and is fixed in contact with the surface portion of the base body at the step portion, The cylindrical body can be joined under stable conditions.

  Further, in the present invention, if the sealing agent is a low melting point glass, a pretreatment such as a metallization treatment on the exposed portion of the optical fiber becomes unnecessary.

  Further, in the present invention, if the melting point of the adhesive is lower than that of the sealing agent, the sealing agent is not softened in the bonding between the base and the cylindrical body, so that the airtight defect can be reduced. it can.

  Therefore, according to the present invention, it is possible to provide an optical input / output terminal excellent in long-term reliability in which stress and thermal damage to the optical fiber are reduced.

Hereinafter, an optical input / output terminal according to an embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 1, an optical input / output terminal 1 according to an embodiment of the present invention includes an optical fiber exposed portion 2c in which a part of an optical fiber 2a is exposed and an optical fiber coating in which the optical fiber 2a is covered with a resin or the like. An optical fiber body 2 having a portion 2b, a cylindrical body 3 accommodating at least the optical fiber exposed portion 2c, a sealant 4 disposed so as to close the inner hole 3a of the cylindrical body 3, and a cylindrical body And a base 5 for fixing 3. In addition, the optical fiber exposed part 2c points out the site | part which removed the resin-made coating | covers around the optical fiber body. Specifically, the optical fiber exposed portion 2c refers to a portion constituted by a core and a clad covering the periphery of the core.

  The optical fiber exposed portion 2c is separated from the inner peripheral surface 3b of the cylindrical body 3 via a gap in the insertion portion 3c of the cylindrical body 3, and the sealing agent 4 is a cylindrical body excluding the insertion portion 3c. 3 is disposed between the inner peripheral surface 3b and the optical fiber exposed portion 2c. Here, the insertion portion 3c refers to a portion of the cylindrical body 3 that is inserted into the through hole 5a of the base body 5, and is indicated by a double solid line in FIG. The non-insertion portion 3d refers to a portion of the cylindrical body 3 that is not inserted into the through hole 5a of the base body 5, and is indicated by a double dotted line in FIG.

  In the conventional optical input / output terminal, since the sealing agent 4 is in the insertion portion 3 c of the cylindrical body 3, stress concentration on the sealing agent 4 due to a difference in linear expansion coefficient from the base body 5 cannot be excluded. It was. However, in the present invention, by providing the sealant 4 in the non-insertion portion 3d of the cylindrical body 3, it is possible to eliminate stress concentration on the sealant 4 due to a difference in linear expansion coefficient with the base body 5, Breakage of the optical fiber exposed portion 2c can be suppressed.

  The cylindrical body 3 has an opening 3e and a groove 3f. The opening 3e is for injecting the sealing agent 4. The sealing agent 4 is injected from the opening 3e of the cylindrical body 3, and as shown in FIG. 1, the opening 3e and the groove 3f At the position, the inner hole 3a of the cylindrical body 3 is sealed. The groove 3f may be formed on the inner peripheral surface 3b of the cylindrical body 3 so as to face the opening 3e, or the circumferential direction of the inner peripheral surface 3b at the same position as the opening 3e in the longitudinal direction of the cylindrical body 3 You may form in. When the groove 3f is formed in the circumferential direction of the inner peripheral surface 3b at the same position as the opening 3e in the longitudinal direction of the cylindrical body 3, the groove 3f and the opening 3e may be continuous or separated from each other. Good. If the groove 3f and the opening 3e are continuous, the sealing agent 4 injected from the opening 3e is filled through the groove 3f formed on the inner peripheral surface 3b. It becomes difficult to flow to a position different from the positions of 3f and the opening 3e. In addition, after the sealant 4 has hardened, the groove 3f as described above is formed, so that the engaging portion between the sealant 4 and the cylindrical body 3 becomes larger. The locking with respect to the cylindrical body 3 is good. Furthermore, as described above, by forming the groove 3f along the circumferential direction of the inner peripheral surface 3b, the sealing agent 4 can be more securely locked to the cylindrical body 3.

  Further, as shown in FIG. 1, the optical input / output terminal 1 may have a protective tube 8 having heat resistance between the cylindrical body 3 and the optical fiber body 2, and the protective tube 8 is a cylinder. The optical fiber body 2 is inserted into both protective tubes 8 by being fitted to both ends of the body 3. By setting it as such a structure, the optical fiber coating | coated part 2b can be protected from the influence of the heat | fever at the time of sealing.

  Furthermore, the cylindrical body 3 may be provided with a stepped portion 3g as shown in FIG. In this case, the step 3 g is brought into contact with the wall 5 b around the through hole 5 a of the base 5, and the cylindrical body 3 is fixed to the base 5 with the bonding agent 6. Thus, in the optical input / output terminal 1, the stepped portion 3 g is provided and brought into contact with the wall portion 5 b around the through hole 5 a of the base body 5, and the cylindrical body 3 is fixed to the base body 5 with the bonding agent 6. The accuracy can be improved and the fixing of the cylindrical body 3 to the base body 5 can be strengthened. Before the bonding agent 6 is solidified, the cylindrical body 3 is easily displaced with respect to the base 5, but before the bonding agent 6 is solidified by bringing the step portion 3 g into contact with the wall 5 b of the base 5. Also, the cylindrical body 3 is less likely to be displaced with respect to the base body 5.

Hereinafter, a specific configuration of each member will be described.
As shown in FIG. 1, the optical fiber body 2 includes an optical fiber 2a and an optical fiber covering portion 2b that covers the optical fiber 2a. Furthermore, the optical fiber body 2 has an optical fiber exposed portion 2c in which at least a part of the optical fiber covering portion 2b is removed and the optical fiber 2a is exposed. Any optical fiber 2 may be used. For example, a quartz optical fiber may be used.

The cylindrical body 3 holds the optical fiber body 2 and is inserted into a through hole 5a of the base body 5 described later. In the inserted state, the optical fiber exposed portion 2 c of the optical fiber body 2 is disposed in the inner hole 3 a of the cylindrical body 3. Moreover, the cylindrical body 3 may have the opening part 3b for performing positioning of the sealing agent 4, and the groove part 3c, as shown in FIG.
Further, as shown in FIG. 2, the cylindrical body 3 may have a step portion 3g having a diameter larger than that of the insertion hole 5a in order to contact and fix the base body 5 with the insertion hole 5a.

  Examples of the material constituting the cylindrical body 3 include metal (stainless steel, Fe—Ni—Co alloy, copper, iron, nickel, and the like), ceramics (such as aluminum oxide (alumina) and zirconium oxide (zirconia)), and glass (quartz). Etc.). Among these, it is preferable to use an Fe—Ni—Co alloy in the same manner as the base 5 in order to increase the reliability by combining the thermal expansion coefficient in consideration of the case of using the low melting point glass for joining with the optical fiber exposed portion 2c.

  The sealant 4 is filled in the inner hole 3a of the cylindrical body 3, and completely seals between the optical fiber 2 and the inner peripheral surface 3b of the cylindrical body 3 in the optical fiber exposed portion 2a. . The material of the sealant 4 may be solder or low melting point glass. When solder is used as the sealant 4, a metal film may be applied to the surface of the optical fiber 2a in the optical fiber exposed portion 2c in advance from the viewpoint of improving the wettability of the solder, for example, by electroless plating. As such a metal film, for example, a Ni layer as a base and Au plated thereon may be used. Moreover, when low melting glass is used as the sealant 4, there is a cost merit because no pretreatment is required for the optical fiber 2 a.

  The solder type may be any of Pb / Sn solder, Au / Sn solder, Ag / Sn solder, etc., but it is desirable to use lead-free solder in consideration of European RoHS regulations.

Some types of low-melting glass are mainly composed of lead oxide, boron oxide, etc., but have a coefficient of thermal expansion larger than that of the exposed portion 2c of the optical fiber so that a compressive stress is applied to the optical fiber 2a. It is desirable to select one having a thickness of 5 to 10 × 10 ⁻⁶ / ° C.

For example, as an example of a combination of members having such a thermal expansion coefficient, the optical fiber 2a is quartz (thermal expansion coefficient: 0.5 × 10 ⁻⁶ / ° C.), and the sealing agent 4 is lead oxide or boron oxide. And low-melting glass comprising a bismuth oxide material (thermal expansion coefficient: 8 × 10 ⁻⁶ / ° C., glass transition point: 215 ° C.).

  The viscosity of the sealant 4 is preferably 10 Pa · s to 300 Pa · s, and more preferably 30 Pa · s to 200 Pa · s. If the viscosity of the sealant 4 is within such a range, the sealant is less likely to flow through the inner hole, and the inner hole 3a can be accurately sealed at the positions of the opening 3b and the groove 3c.

  The protection tube 8 is inserted between the cylindrical body 3 and the optical fiber coating portion 2b in order to protect the coating resin portion of the optical fiber coating portion 2b from the influence of heat during sealing. By disposing the protective tube 8 in this way, heat conduction from the tubular body 3 to the optical fiber covering portion 2b can be prevented. The protective tube 8 and the optical fiber 2 are fixed with an adhesive 7. The protective tube 8 also serves as a bend limiter so that the optical fiber exposed portion 2c is not damaged even if the optical fiber body 2a is pulled. As a material for the protective tube 8, a heat-resistant polyimide-based or fluorine-based resin is desirable. These are preferable because they can withstand high temperatures.

  The bonding agent 6 is for bonding and fixing the cylindrical body 3 to the base body 5. As such a bonding agent 6, solder, low-melting glass, ceramic adhesive, polyimide adhesive, or epoxy adhesive can be used. The bonding agent 6 preferably has a lower melting point than the sealing agent 4. Accordingly, even when heat is applied to melt the bonding agent 6 in the bonding of the base body 5 and the cylindrical body 3, the softening of the sealing agent 4 due to the heat can be prevented. The occurrence of poor airtightness due to can be further reduced.

  The adhesive 7 is for bonding and fixing the protective tube 8 to the cylindrical body 3. As such an adhesive 7, an epoxy adhesive, an acrylic adhesive, a silicone adhesive, or a cyanoacrylate adhesive can be used. Epoxy adhesives are preferably used because they have increased hardness after heat curing and excellent adhesion.

  FIG. 3 shows an embodiment provided with a plurality of optical input / output terminals according to the present invention. In this embodiment, each optical input / output terminal is fixed to the same base 5. Since the optical input / output terminal may require a plurality of optical fibers depending on the application, the optical input / output terminal may include a plurality of optical input / output terminals fixed by the common substrate 5 as in the above embodiment. In such a configuration, for example, an optical fiber is introduced from the outside to the inside of the housing while maintaining the airtightness between the outside and the housing by being incorporated in a part of the housing that wants to ensure airtightness with the outside. Is possible.

(Optical input / output terminal manufacturing method)
Hereinafter, a method for manufacturing an optical input / output terminal according to the present invention will be described in detail.

  First, the optical fiber body 2 in which the optical fiber 2a is covered with the optical fiber covering portion 2b is prepared. And as shown to Fig.4 (a), the optical fiber coating | coated part 2b is removed from the optical fiber 2a in a sealing location, and the optical fiber exposed part 2c is formed. Here, the removal of the optical fiber covering portion 2b can be performed by melting the optical fiber covering portion 2b by chemical treatment. In this case, physical damage to the optical fiber 2a can be efficiently reduced. When solder is used as the sealant 4, the surface of the optical fiber 2a in the optical fiber exposed portion 2c may be subjected to a surface treatment such as metallization, thereby improving the wettability of the solder. it can.

  Subsequently, two protective tubes 8 having through holes are prepared. As shown in FIG. 4B, the optical fibers 2 are inserted into these protective tubes 8, and the protective tubes 8 are respectively arranged and fixed on the optical fiber covering portions 2b on both sides of the optical fiber exposed portion 2c. The protection tube 8 and the optical fiber 2 may be fixed using an adhesive, or by attaching the protection tube 8 having a smaller diameter than the optical fiber coating portion 2b to the optical fiber coating portion 2b. Good.

Furthermore, as shown in FIG. 4C, the optical fiber 2 to which the protective tube 8 is mounted as described above is inserted into the inner hole 3a of the tubular body 3 made of Fe—Ni—Co alloy, for example. The cylindrical body 3 is arranged so that the fiber exposed portion 2c is positioned in the inner hole 3a. The protective tube 8 is disposed between the cylindrical body 3 and the optical fiber 2 and plays the role of a bend limiter.
The outer surface of the cylindrical body 3 may be subjected to gold plating with Ni as a base in consideration of solder bonding with the base 5.
The size of the cylindrical body 3 is arbitrary and is appropriately set in consideration of the dimensions of the optical fiber to be incorporated and the protective tube 8.

  Next, as shown in FIG. 4 (c), low melting point glass (sealing agent 4) containing lead oxide, boron oxide, and bismuth oxide material is introduced from the opening 3b formed in the cylindrical body 3. Then, the portion is locally heated with a high-frequency induction heating device or the like to melt and seal the sealant 4.

  Next, as shown in FIG. 4 (d), the cylindrical body 3 in which the optical fiber exposed portion 2 a is sealed with the sealing agent 4 is inserted into the through hole 5 a of the base body 5, thereby forming the cylindrical body 3. The stepped portion 3 g is brought into contact with the wall portion 5 b around the through hole 5 a of the base 5 to fix the cylindrical body 3 to the base 5. In that state, the portion is locally heated by a high-frequency induction heating device or the like, and bonded with a bonding agent 6 such as Au / Sn solder, for example.

Finally, the cylindrical body 3, the protective tube 8, and the optical fiber 2 are fixed with an adhesive 7. As shown in FIG. 1, the protective tube 8 and the cylindrical body 3 are joined by applying an adhesive 7 to the region A formed by the outer surface of the protective tube 8 and the end surface of the cylindrical body 3. it can.
By the above manufacturing method, the optical input / output terminal according to the present invention having excellent long-term reliability can be produced.

It is sectional drawing of the optical input / output terminal which concerns on one embodiment of this invention. It is sectional drawing of the optical input / output terminal which concerns on another embodiment of this invention. It is sectional drawing of the optical submarine cable repeater using the optical input / output terminal of this invention. It is process drawing of the manufacturing method of the optical input / output terminal which concerns on this invention. It is sectional drawing of the optical input / output terminal of a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical input / output terminal 2 Optical fiber body 2a Optical fiber 2b Optical fiber coating | coated part 2c Optical fiber exposure part 3 Cylindrical body 3a Inner hole 3b Inner peripheral surface 3c Insertion part 3d Step part 3e Opening part 3f Groove part 3g Step part 4 Sealing Agent 5 Substrate 5a Insertion hole 5b Wall 6 Bonding agent 7 Adhesive 8 Protective tube

Claims (7)

An optical fiber body including an optical fiber and an optical fiber covering portion that covers the optical fiber, and having an optical fiber exposed portion where the optical fiber is exposed in at least a part of the optical fiber covering portion;
A cylindrical body having an inner hole in which at least the optical fiber exposed portion is accommodated;
A sealant disposed between the inner peripheral surface of the cylindrical body and the exposed optical fiber, and sealing a part of the inner hole;
Including at least one through-hole for holding the cylindrical body, and a base for fixing the cylindrical body by inserting at least a part of the cylindrical body into the through-hole,
The optical fiber exposed portion is spaced apart from the inner peripheral surface of the cylindrical body via a gap in the insertion portion inserted into the through hole of the cylindrical body,
The optical input / output terminal, wherein the sealant is disposed between an inner peripheral surface of a non-insertion portion of the cylindrical body excluding the insertion portion and the optical fiber exposure portion.   2. The light according to claim 1, wherein the cylindrical body has a groove portion on an inner peripheral surface of a portion where the sealing agent is disposed, and a part of the sealing agent enters the groove portion. Input / output terminal.   The optical input / output terminal according to claim 1, wherein the groove is formed over the entire circumference of the inner peripheral surface of the portion where the sealant is disposed.   The said cylindrical body has a level | step-difference part larger than the diameter of the said through-hole in an outer peripheral surface, It contact | abuts to the surface part of the said base | substrate at this level | step-difference part, and is fixed. The optical input / output terminal according to any one of the above.   The optical input / output terminal according to claim 1, wherein the step portion and the surface portion of the base are fixed with an adhesive.   The optical input / output terminal according to claim 1, wherein the sealant is made of low-melting glass.   The optical input / output terminal according to claim 6, wherein the adhesive has a melting point lower than that of the sealing agent.

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